Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's Disease, is a fatal neurological disease that rapidly attacks and destroys the nerve cells that are responsible for voluntary movement. The destruction of the neurons in the brain and spinal cord that control movement eventually progresses to the point that all voluntary motor control is lost. Death typically occurs from respiratory failure within 3-5 years of disease onset.
Approximately 20,000 people in the United States have ALS, and 5,000 people are diagnosed with ALS each year. ALS is common worldwide, affecting people of all races and ethnic backgrounds. The average age of onset of ALS is between 40 and 60 years of age, but ALS can strike both younger and older men and women. In 90-95% of ALS cases, the disease is apparently random (known as sporadic ALS (SALS)). In such SALS cases, there is no family history of the disease and no clearly associated risk factors. In 5-10% of ALS cases there is an inherited genetic link (known as familial ALS (FALS)).